Visible light photoelectrochemical sulfide sensor based the use of TiO2 nanotube arrays loaded with Cu^sub 2^O

This work describes a photoelectrochemical for sensing sulfide method that is based on TiO2 nanotubes loaded with Cu2O particles (Cu2O/TiNTs). The narrow band gap of Cu2O and the heterostructure at the interface between Cu2O and TiO2 in the Cu2O/TiNTs significantly enhance visible light absorption and charge separation, and these results in an improved photocurrent of the Cu2O/TiNT electrode under irradiation with visible light (> 400 nm). In the presence of sulfide, Cu7S4 is formed on the surface of the Cu2O/TiNT, this leading to a decrease in the photocurrent on the electrode. At a potential of 0.0 V, the photocurrent of the Cu2O/TiNTs before and after immersing it into 300 μM sulfide solution is 1086 and 310 μA cm−2, respectively. The findings were used to design a photoelectrochemical sulfide sensor. Under optimum conditions and at a pH value of 7.0, the change in photocurrent varies linearly in the 1 to 300 μM sulfide concentration range with a 0.6 μM detection limit. The sensor was applied to the determination of sulfide in spiked real water samples. [Figure not available: see fulltext.]